Fuse



A. L. EUSTICE April 1, 193().

FUSE

Patented Apr. l, 1930 UNITED STATES ALFRED L. EUSTICE, OF CHICAGO, ILLINOIS FUSE Application led December 1, 1921. Serial No. 519,159.

The present invention relates to fuses.

The present invention has been illustrated herein in connection with a plug fuse and, as will appear hereinafter, has decided advantages in a fuse of this type, though, in its broader aspects, the present invention has a wider field of applicability than plug fuses.

An object of the present invention is to provide a fuse which has a great uniformity of operation.

A further object is to provide a fuse of the plug type in which the fusible element will blow at a predetermined point which is plainly'visible, thereby doing away with the uncertainty as to whether or not a fuse is in operative condition.

A- further object is to provide a fuse of the plug type which is very simple to manufacture and which therefore adapts itself readily to quantity production on a commercial basis.

Y Further objects will appear as the description proceeds.

Referring to drawings,

Figure 1 is an end view illustrating one embodiment of the present invention.

Figure 2 is an end View of the embodiment illustrated in Figure 1, but taken from the opposite end of the fuse.

Figure 3 is a transverse sectional view.

Figure 4 is a view illustrating the fusible element independently of its Aco-operative parts.

Figures 5 and 6 are views in perspective illustrating the two sides of one of the parts of the fuse.

Figure 7 is a contact member used in the improved fuse.

Figure 8 is a view illustrating the manner of constructing the fusible element.

As perhaps best illustrated in Figure 3, the fuse according to the present invention comprises a pair of holding members 10 and 11 which should be of insulating material capable of being molded, such as hard rubber. Member Y 10 comprises a cylindrical member which may be provided with screwthreads 12 for a purpose which will be apparent hereinafter. The member 11 comprises a cap member adapted to abut one end of the cylindrical member 10. The cap member 11 is held in fixed relation with the cylindrical member 10 by means of the shell or casing 13, which may be of relatively thin conducting material, swaged to form screwthreads 14-111 co-operating with the screwthreads 12-12. The shell 13 will also have a turned over end portion 15 for engaging the outer side of the cap 11.

Mounted centrally of the cap 11 is 'the contact member 16, provided with the head 17 and the shank 18, which shank lies axially of cylindrical member 10. The fusible element, which is indicated by the numeral 19, is provided with a hole 20 for vthe reception of the shank 18 of the contact member 16. Said fusible element 19 is bent intermediate of its length in a plurality of places whereby to tit within the chamber formed by the cylindrical member 10. The shank 18 of the contact member 16 may be upset after the fusible element has been mounted thereon, and a rigid connection between said fusible element and said shank 18 may be ensured by soldering said members together. The contact member 18 should be firmly held within the cap 11 between the abutments formed by the head 17 and the end of the fusible element 19. Rotating movement of the contact member 16 may be prevented by the construction illus'- trated, comprising a lug 21 on the head '17, which lug 'lits within the corresponding recess 22 in the cap member 11. In orderto properly hold the cap member 11 1n proper position'relative to the cylindrical member 10, said cap member may be provided with an outstanding lug 23 adapted to tit more or less closely within a corresponding recess in the co-operating end of cylindrical member 10. By reason of the fittingof lug 23 Within its corresponding recess, the cap member will be stopped as regards any tendency toward'ro. tation, whereby the fusible element will always be held in its proper position within the cylindrical member 10. i

As indicated in Figures 3 and 4, the fusible element 19 comprises the end portion 24 lying in proximity to the cap 11. Said fusible element is provided with a portion 25 lying in a position along the inner wall of the cylindrical member and has another portion 26 lying substantially normal to the axisl of the cylindrical member 10. Another portion 27 of the fusible element lies in proximity to the inner wall of the cylindrical member 10, being spaced from the member 25, and extending to a point adjacent to the plane of the end portion 24. Fusible element A19 has .a portion 28 which may overlie the end of the cylindrical member 10, being located within a slot in said end, whereby the outer side of the fusible member 19 will lie approximately in the same plane as the end of cylindrical member 10.

Fusible element 19 is provided with still another bent-over portion 29 adapted to lie in a corresponding slot on the outside of cylindrical member 10. The portion 29 of the fusible element 19 may have its outer surface engaged bythe threaded shell or casing 13.

It will be evident without detailed descri tion that when the cap member 11, with t e fusible element mounted thereon, is applied to the left-hand end of the cylindrical member 10, as viewed in Figure 3, said members may be held in fixed relation by means of the screw-threaded shell 13. The shell 13 will have a good electrical connection with the end portion 29 of the fusible element 19 by reason of the contact of the screwlthreads 14-14 of said shell with said end portion 29.`

In order to further ensure a perfect contact, said shell member 13 may be soldered to the end portion 29 of the fusible element 19, as indicated by the numeral 30, (Figure 3).

' The right-hand end of the cylindrical member 10 isprovided with an enlarged grip portion 31 b means of which the p ug fuse may be rea 'ly manipulated.- Said righthand end of the plug fuse is provided with a sight openin 32 which may be provided with a mica, g ass or other transparent closure 33. Said closure 33 ma be held in place by any preferred means, w ich means need not be described herein inasmuch as they are well known and constitute no part of the present invention.

The fusible element 19 is rovided, at a point clearly visible through t e sight openm132, with a pair of opposed notches pro'- vi 'ng a restricted portion 34. Experimentation and practical emonstration have shown that the number of restricted portions in a fusible element should referably be an odd number. According to t e present invention, three restricted portions are illustrated, one of which lies in the portion of the fusible link and the other of which lies in the portion 27 of the fusible link, both of said restricted ortions bein indicated by the 'numeral 35. e4 restricta portions 35-35 should preferably be located substantially symmetrically with respect to the restricted portion 34. Said restricted ortion 34 may, with advantage, be located) substantially midway between,tl1etwo terminals of the fusible element. The restricted portions 35-35 and 34 may be of substantially the same dimensions, or portion 34 may present less metal than does either of the portions 35. The reason for this construction need not be discussed herein, but it may be stated briefly that the -center restricted portion 34 will melt and break the circuit, either on slight overload beyond the capacity of the fuse, or upon very heavy overload.,l such as accompanies a short circuit. The restricted portions 35-35, flanking the restricted portion 34, ensure the melting of the center restricted portion in all cases in which it is required that the fusible element should melt. The restricted portion 3 4 is located directly in front of the sight opening and in close proximity thereto, and inasmuch as the fuse will invariably melt at this point, there is no reason for uncertainty as to whether or not a fuse has blown. The term in front of the sight opening, as apparent from the drawing, refers to a position inwardly of the fuse relative to the sight opening. In other words, the termffront as used in this connection refers to a position toward the head 17 of the fuse.

For convenience in assembling on' a quantlty basis, each of the elements of the fuse shouldA be provided with locating means whereby the fuses will invariably be put together in the same relation. For this purpose, and for a further purpose which will be stated shortly, the cap member 11 is provided with holes 36--36. The right-hand end cylindrical member 13 may be provided with a locating hole 37. The non-cylindrical parts of the fuse will rovide their own locating means. The fusi le element 19 will preferably be bent into the required shape by machine Furthermore, the Contact member 16 wil be inserted within the cap member 1l, with the lug 21 fitting Within recess 22, and the fusible element will be attached by machinery. The cap member 11 will then be applied to the cylindrical member 1'0, the

roper angular relation in the machinery ing ensured by the locating holes 36-36 and 37. Engagement of lug 23 will prevent turning of cap member 11 relative to cylindrical member 10 while the machinery is turnin up the threaded shell` 13. Thereafter t e machinery will swage the turned over portion 15 of shell 13, whereby parts thereof will lie within the holes 36-36 of the cap member 11 to hold the shell member 13 against rotation.

In order to improve the visibility of the fusible element 19, that portion of said fusible element which is visible through the sight opening 32 may be painted a light color, or may be painted with luminous paint. This expedient is of importance, inasmuch as fuses are frequently located in very dark ,closets or corners. In making the fusible elements, said elements may be struck from a blank nsuch as illustrated in Figure 8. Said blank, Which is indicated by the numeral 38, may be provided with a band of luminous or other highly visible paint intermedia-te of its yWidth.- Figures may be stamped on a visible portion of the fusible element indicating the capacity vof the fuse in amperes. VThefuse elements may be struck from a blank 38 and bent into the form shownin Figure 4, in which case the restricted portion 34, with the luminous paint covering that region of the fusible element, Will `lie in a position to be visible through the sight opening 32 of the fuse. Y

I do notdesire to have the scope of my invention limited to plug fuses, inasmuch as the advantages of the present invention are applicable to other types of fuses. One em bodiment of the present invention has been described in detail. `Manymodiications will occur to those skilled in the art. It is intended in this patent to cover all such modiiications that fall Within the scope of the invention as defined by the appended claims.

I claim:

l. An electric fuse comprising a substantially closed receptacle having a sight opening and a fusible element mounted Within said receptacle, said fusible element having a plural odd number of restricted portions, the central one of which is located substantially symmetrically with the remainder of said restricted portions, said central restricted portion being located directly in front of said sight opening to be readily visible through said sight opening.

2. An electric use comprising a receptacle providing a substantially closed chamber, a cap for said chamber, and a fusible element arranged along the walls of said chamber, said fusible element having a plural odd number of restricted portions, said chamber having a sight opening, the central one of said restricted portion being positioned directly in front of said sight opening to be readily visible through said sight opening.

3. An electric fuse comprising a cylindrical member, a cap member for one end of said cylindrical member, a contact member located centrally of said cap member, said contact member having a head portion and an upset shank portion, threaded conducting means providing an electrical terminal and uniting said cylindrical member and said cap member, and a. fusible element connected to said contact member by means of said upset shank portion and also being connected to said threaded means, said cap member being provided With a plurality of holes suitable for locating said cap member relative to said cylinder member in assembling, said conduct ing means being swaged into said holes to prevent rotation of said metallic conducting member.

4. An electric fuse comprising a cylindrical member, a, .can mmberffor. ensendefsi1-id cylindrical member; ajfcontact y.inclnbc'rl; lcated Vcentrally of said capI member, said, 'contact member havingla'head portionA and an, p- St Shank portifimtheidd r'ldiletifs' ,111

providing an electric t v `rinnal', and said cylindrical; nieinb'er andz said capy meinbeiQUand a fusibleeleinentconnected to said contact member 'by means of' saidiips'et shank portion, and also. beingfeoneetedzto'; said threaded means, said" cap nieniberbeing-provided with al plurali'tyofg'lioles suitable foi" 5. Anelcctificfuse comprising afcylindrical i member, a cap member for one lend fther'eof, and a metallic memberf'gha'vingl. screwthreaded engagement with said cylindrical member for holding said cap memberin pijoper relation to sa-id,cylindrical member,` said cap member being providedrvith a plurality of holes on the outer side thereof suitable ,for locating saidy cap Amember relativegtof said cylindrical member in ,.iassembling, A said metallic amending. merabe1?.fy being@ srged mt@ Said 11019510 Prerent rrotaztien--effsazid metallic conducting member.. ,i

6. An electric fuse e ,coniprisili-g;l a chainber 11a-vinse :Sieht Qpninsyawfusible ,element `mounted ywithin said chamber ,and having electrical connection at Y eachi-en'd thereof with the exteriorojfsaifd chambensaid fusible element having a lrestricted portion substantially midwayfbetiveen said exterior eleci., tricalconnections, the tregion yof said fusible element adjacent to said restrictedporticn being covered With paint of visibility, said restricted portionbcingelocated a position to be visible through said sight ,opening-VL, l v

having a. vsight opening,a lfusiblefelement located Within' said chamber andlhaving an elec trical connection at eachv end thereof with the exteriorof saidI chamber, said fusible elementl having an odd nuinberofrestfrijc'ted portions, of'whic'h the central restricted portion is sym metrically arranged'relative tothe'otherr'estrictcd portions, said centralfrestrictedporvtion being" located in apositionto visible'g` through said Sight Openingg'the region offfsaid fusible element" adjacent to :said central *restricted 'portion beingcovered nwith lpaint 'of high-visibility a l i l .8.' An electric fusecomprising,alreceptaclege having a sightopening-anda .fusible element mounted. within said receptaclmlsaid, fusible dis-fig vico l1,110 7. An electric fuse comprisingla chambr` element'liaving an odd number of restricted portions, the central one of: isflccated t substantially vvithgthe i .re-f, l,

ment havin a luminescent and fusible portion locate to be viewed through the plug window.

11. A fuse plug of the window ty e provided with a current carrying fusi le element havin luminous paint applied to la surface thereo visible through the plug window.

12. A fuse plug bf the window ty provided with a current carrying fusi le element of an elon ated form and having luminous paint applied to a fusible portion thereof visible through the plug window.

13 An electric fuse comprising a substantially closed receptacle having a sight opening and a fusible element mounted within said receptacle, said fusible element having a plural odd number of restricted ortions, the central one of which is located in a position in close proximity to said sight opening and directl in front of'said sightopening.

14. n electric fuse comprising a substantially closed rece tacle having a sight opening and a fusib e element mounted within said rece tacle, said fusible element havina plural d number of restricted portions, t e central one of which is located substantially symmetrical with the remainder of said restricted portions, said central restricted portion being located in a position directly-in front of said sight opening and in close proximity to said'sight opening.

15. An electric fuse comprising a substantially closed receptacle having a sight openin and a fusible elementI mounted within said receptacle, said fusible element having a plural odd number of restricted portions, the central one of which is located in a position Y in close proximity to said sight opening and directly in front of said sight opening, said restricted portions having substantially the same dimensions.

16. An electric fuse comprising a substanportions having substantially the same dimensions.

17. An electric fuse comprising a substan- I tially closed receptacle having a sight opening and a fusible element mounted within said receptacle, said fusible element having a plural odd number of restricted portions, the central one of which is located substantially symmetrical with the remainder of said restricted ortions, said central restricted portion bein ocated in a position directly in front of sai sight opening and in close proximit to said sight opening, the central restricte portion presenting no more metal than do the other restricted portions, said other restricted portions having substantially the same dimensions- Signed at Chicago, Illinois, this 26th day of November, 1921.

ALFRED L. EUSTICE. 

